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Boxster started hesitating when accelerating?

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So the other night I was talked into letting my girlfriends brother drive my 99 boxster 2.5l. To say the least, im preatty sure he burned up my clutch. I could smell it and I could tell by the way he was letting it out so slowly. Well when I got back in the driver's seat I realized the car seemed to be shuttering or hesitating whenever i would give it more than minimal gas needed for acceleration. Usually it happens right around 3k rpms. I was assuming that it was the clutch starting to go.. I looked around on pelican and some other forums and would probably end up doing the clutch myself if it came to it. But I guess Im just wondering if there is something else that may be going on? Does something need to be adjusted? Replaced? Any help or pointers are greatly appreciated.

99 Boxster Base

97k Miles

2.7 liter 5 Speed


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Hey Loren, no I haven't checked for fault codes yet. I'll hook my computer up and see if anything shows. If not, would I be able to swing by sometime and take you for a quick ride? You'd know better than I if it really is the clutch

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P1123 Oxygen Sensing Adaptation Area 1 (Cylinders 1 - 3) - Lean Threshold

P1125 Oxygen Sensing Adaptation Area 1 (Cylinders 4 - 6) - Lean Threshold

Possible causes:

- Fuel pressure too high.

- Fuel injector leaking.

- EVAP canister purge valve open.

This means your car is seeing too rich a mixture - so rich that the DME can not correct for it.

Many times this is the EVAP purge valve.

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I have a similar issue. I have a 99 Boxster 2.5l with 51k miles. looks just like the picture above, but more tools scattered around. I have been getting the same codes and I have cleared them several times. Always after I idle a bit putting the top up, and chilling before going into work. Work is a 17 mile trip at 55mph.

I cleaned the Map sensor with electronics spray.

The trims from a Xnova scan tool from memory both banks about the same.

ST -5.14

LT 24.xx some as high as 30.

Several erase cycles later.....

This morning Made smoke tester, and used brake cleaner spray. No leaks found. Checked AOS it does allow a vacuum into the Crankcase, but not excessive to hold cap down. When cap is removed the idle gets slightly faster, and rougher.

Checked vacuum canister circuit, holds vacuum - one way valve works. Evap circuit is not leaking- tried to pull a vacuum on it, holds vacuum. ( how do you hold vacuum???)

Smoke test saw smoke come out of oil cap, no where else.

Tested vacuum when running. 18 inch hg up to 22 at higher RPM.

fuel spec is 3.3 and 3.8 bar, which is 47.8psi to 55.1psi

Checked after tightening fuel tester 47 psi running, 55psi static, and with regulator V hose removed. Fuel pressure good.


fuel pressure good

Evap valve seems closed

vacuum canister holds vacuum.

AOS passes some flow but filler cap is not sucked in and throttle body is dry.

Light oil in the J tube to AOS

smoke test with home made tester- no leaks.

only at idle is mixture trimmed rich I think.

Need live data scan tool.

Thought I would post this data point, See if there are any ideas, keep posting my saga in hopes that it may help someone besides myself.

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